Overload release coupling



July 17, 1951 M. A. RICHARDSON 2,561,136

OVERLOAD RELEASE COUPLING Filed July 4. 1945 2 Sheets-Sheet 1 2/ 22 l 4Z7zz/ierai07f j aiizlzdi. Eickardsow J 1951 M. A. RICHARDSON 2,561,136

. OVERLOAD RELEASE COUPLING 2 Sheets-Sheet 2 Filed July 4, 1945 PatentedJuly 17, 1951 Martin A. Richardson, Racine, Wis., asslgnor to J, I. CaseCompany, Racine, Wis., a corporation of Wisconsin Application my 4, 1m,-serau No. 603,129

1 Claim. (01. iii-e9) This invention relates to overload release or jumpclutches adapted to be incorporated in' right-angle driving trains, moreparticularly to clutch and drive mechanisms for agricultural machinery,and the invention hasfor an object the provision of inexpensive, ruggedand compact mechanisms of this character.

In varying types of agricultural machinery,

such as combines, pickers, harvesters and mowers, for example, it iscommon practice to provide an overload release or jump clutch in thedriving trains between the power shafts and the work-performingimplements, such for example as tion relative to the shaft, is providedwith a clutch mechanism which includes a first clutch member secured tothe shaft and having a radially extending disc portion one face of whichincludes means forming a serrated clutch surface. Surrounding the shaftadjacent the disc portion is the cutters of mowing machines or thebundle carriers of harvesters, in order to provide overload relief andavoid breakage of the parts in the event that the work-performing.implement should become jammed. v

Where the overload release or jump clutch is part of a right-angle driveembodying a chain and sprocket for example, it has been proposed toemploy the sprocket itself as one element of the clutch by formingsuitable serrations or notches on one face of the sprocket at the timethe sprocket is cast. It has been found advisable,

however, and in fact necessary when the chain drive embodies closecenters or when roller chains are used, to construct the jump clutch insuch a manner that the sprocket will remain axially stationary on theshaft and will not oscillate during the jumping action. In other drives,where light loads are involved and light ribbon chains on relativelywell-spaced centers are employed,

movement of the sprocket during jumping of the clutch may not beobjectionable and in such cases less costly constructions may beemployed. In either case, however, the use of'cast clutch parts isobjectionable, since the. clutch faces wear out rather quickly eventhough the parts are cast with a chilled face, and the forming of theclutch face integral with the sprocket militates against standardizationand increases replacement expense.

Accordingly, it is a further object of this inventionto provide improvedjump clutch constructions for right-angle drives in which'only a fewdrop-forged parts are employed, which parts may be used interchangeablyin different clutch structures to provide compact and rugged jumpclutches having a long operating life.

In carrying out the invention in one form, a right-angle drive,including driving and driven torque-transmitting elements one of whichcomprises a rotatable shaft and the other of which comprises a toothedelement'journaled for rotaare provided, the spring means being yieldableI an annular clutch member having a coacting serrated clutch surface,and means are provided for mounting the annular membsr for rotation intorque-transmitting relation with the toothed element and for axialmovement relative to the shaft and the first clutch member. Spring meansnormally urging the annular member toward the first clutch member tomaintain the serrated surfaces in clutching engagement so as to transmittorque between the driving and driven elements under overload conditionson the serrated faces to permit axial movement of the annular mem-. berout of clutching and torque-transmitting engagement with the firstclutch member.

For a more complete understanding of the invention, reference should nowbe had to the drawings in which: Fig. 1 is an elevational sectional viewshowing a jump clutch construction embodying the present invention;

Fig. 2 is an end view of the clutch construction shown in Fig. 1;

Fig. 3 is an elevational detail view of one of.

the clutch members employed in the clutch construction of Fig. 1;

Fig. 4 is a similar detail view of the other clutch member employed inthe clutch construction of Fig. 1;

Fig. 5 is a fragmentary developed view showing the shape of theclutching members of Figs. 3 and 4;

Fig. 6 is an elevational sectional view of another form of jump clutchconstruction embodying the invention;

Fig. 7 is an end view of the clutch construction shown in Fig. 6;

Fig. 8 is a front face view of one of the clutch members employed in theconstruction of Fig. 7;

Fig. 9 is a rear face view of the clutch member shown in Fig. 8; and

Fig. 10 is a side elevational view of the clutchmember shown in Figs. 8and 9.

Referring now to the drawing, the invention is shown as embodied in ajump clutch mechanism for a right-angle drive comprising a driving shaftAlthough the driven toothed element II is shown as comprising a simplesprocket adapted to be engaged by a suitable chain (not shown), it willbe un derstood that various other types of rotatable elements havingtorque transmitting peripheries may be-employed, and in fact the elementII may be in the form of a pulley, sprocket, gear or cog. Likewise, itwill be understood that the toothed element II may constitute thedriving member of the right-angledrive and the shaft I8 may be thedriven member.

. The shaft III is provided as shown with a shoulder I2 which defines areduced end portion I3 on which is mounted a clutch member I4 having 'ahub I5 and a radially extending disc portion I ever, upon the occurrenceof an overload the I8. The hub portion I5 is provided with a keyway Hfor receiving a Woodruif key I8 whereby the clutch member is securedagainst rotation" relative to the shaft. As shown, the left-hand end ofthe clutch member I4 abuts against the shoulder I2 on' the shaft I8 andis retained against axial movement-on the shaft by a suitable washer I9and a nut 20 which threadedly engages the end of the shaft. The face ofthe disc portion I6 of the clutch member I4 remote from the toothedelement I I is serrated, as shown best in Figs. 3 and 5. o providealternate ridges 2| and notches 22 having sloping surfaces 23.

Although these serrations may be formed in any I suitable manner, theyare preferably formed so. as to extend at an angle of approximately 45degrees, which angularity has been found to provide satisfactory torquetransmission while permitting jumping of the clutch under excessiveloads.

Disposed adjacent the clutch member I4 is an annular clutch member 24which is provided on one face with coacting serrations similar to thoseon the clutch member I4, as shown best in Fig. 4. outwardly of theclutching surface provided by the serrations, the clutch member24 isprovided with a plurality of circumferentlally spaced holes 25 forslidably receiving suitable supporting pins 26 carried by the toothedelement II. As

shown best in Fig. 1,v the pins 26, only one of which is shown, areprovided with threaded ends 21 which extend through suitable holes inthe forces acting on the sloping surfaces 23 on the clutch members willcause the annular member 24 to move to the right, as viewed in Fig. l,on

the pins 28 against the force exerted by the spring 22, and will thuscause the clutch to Jump or slip thereby preventing breakage 'of themachine itself or of parts of the right-angle drive. It will be observedthat during jumping action the toothed element II is maintained in itsaxial position on the shaft in abutment with the clutch member I8 by theforce exerted on the pins 26 by the spring 32. Thus, jumping of theclutch is effected without displacement or oscillation of the toothedelement II on the shaft. The use of a single large spring for urging theclutch member 24 into clutching engagement in place of a plurality ofsmaller'springs, as previously used in jump clutch constructions, is ofparticular advantage, since it has been found that the small springshave a tendency to vibrate at their natural frequency of vibration andoften break toothed element I I and are secured to the toothed element II by nuts 28.

Mounted on the outer ends of the pins 28 is a cup-shapedspring-supporting member 29 which is retained on the pins 26 by suitablenuts or heads 38 and washers 3I, and a clutch spring 32 is mountedwithin the spring support 29, one end of the spring engaging the springcup 29 and the opposite end of the spring bearing against the annularclutch member 24 so as to normally maintain the clutch member 24 inclutching en- .gagement with the clutch member I4.

' The supporting pins 26 as well as the clutch members I4 and 24 mayreadily be formed by drop forging and hardening. Thus hardened clutchsurfaces are provided and the holes in the annular clutch member 24 andthe pins 25 have hard smooth working surfaces thereby providing the bestpossible sliding conditions. The

. arrangement of the clutch pins and the co-operating holes 25 adjacentthe periphery of the clutch member 24 permits accurate centering of theclutch member and the elimination of wobble from the clutch.

It will be apparent from the foregoing that when the shaft I 0 and thetoothed element II are subjected to loads below a predetermined valuethe spring 32 retains the clutch members in torque-transmitting relationso as to couple .vided with a plurality of holes or sockets 49 for orcause the various parts of the clutch to become excessively worn due tothe high frequency of vibration.

In Figs. 6 to. 10 a somewhat simpler form of jump clutch construction isshown which is suitable for somewhat lighterloads than the clutchconstruction shown in Figs. 1 to 5, and which differs in that thetoothed element moves axially of the shaft duri'ng jumping of theclutch. As shown, this modified clutch construction comprises a shaft 40having a shoulder 4| providing a reduced shaft portion 42 and a secondshoulder 43 providing a further reduced shaft portion 44.

Mounted on the reduced portion 42 of the shaft 48 and suitably keyedthereto is a clutch member identical with the clutch member I4 in thepreviously described embodiment of the invention,

and which is identified in Fig. '6 by the same reference numerals. Theclutch member I4 is retained in fixed axial position onthe shaft 48 by abushing 45 which engages, the outer end of the hub I5 .of the clutchmember I4, the bushing 45 surrounding the shaft 44 and being retainedagainst endwise movement by a washer 45 and -a nut 41 which threadedlyengages the end of the shaft. Journaled on the hub I5 of the clutchmember I4 for rotation and for axial movement with,respect thereto is atoothed element or sprocket 48, one face of which is prosupporting intorque-transmitting relation an annular clutch member 50. As shown inFigs. 8, 9 and 10, the clutch member 58 is provided on one face with aplurality of lugs or pins 5| adaptedito be received in the sockets 49 ofthe toothed element 48, and the opposite face of the clutch member 58 isprovided with serrations corresponding to the previously describedserrations on the clutch element I4.

Surrounding the bushing 45 is a spring 52 one end of which bears againsta washer 53 which in turn engages the hub of the toothed element 48.Thus the spring 52 serves to maintain the clutch members I4 and 58 inclutching torquetransmitting engagement and to maintain the clutchmember 58 in torque-transmitting engagement with the sprocket 48 bymeans of the pins 5| and the sockets 49. On the occurrence of overloadconditions the clutch member 50 and the sprocket 48 will move to theright, as viewed in Fig. 6, against the force of the spring 52 so as tointerrupt the torque-transmitting relation the driving and drivenelements I0 and II. Howbetween the shaft 48 and the sprocket 48 and thusprevent breakage or damage to parts of the driving train.

The clutch member 50 may be formed by drop forging in the same manner asthe clutch member l4, and thus hardened clutching surfaces are provided.In case of wear on the clutching surfaces, his not necessary to replacethe entire sprocket 48 but instead a new clutch member 50 may beprovided, thus eliminating expense and permitting continued used of thesprocket 48. If desired, two clutch members identical with the clutchmember 50 may be provided and the disc portion of the clutch member l4may be provided with apertures similar to the apertures 49 in thesprocket 48 for receiving the supporting pins 5! on the second clutchmember 50. In this case, of course, the serrations on the disc portionof the clutch member l4 would be omitted, and in such a constructioneither or both of the clutch members II can be readily replaced in caseof excessive wear. I

While I have shown particular embodiments of my invention, it will beunderstood, of course, that I do not wish to be limited thereto sincemanmmodiflcatiom may be made, and I, therefore, contemplate by theappended claim to cover any such modifications as fall within the truespirit and scope of my invention.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

An overload release clutch mechanism for a right-angle drive includingdriving and driven torque-transmitting elements, one of said elementscomprising a rotatable shaft and the other comprising a rotatableelement journaled for rotation relative to said shaft and having atorquetransmitting periphery, said clutch mechanism comprising a firstclutch member secured to said shaft and having a radially extending discportion, said disc portion having means ,on one face thereof forming aserrated-clutching surface, an annular clutch member surrounding saidshaft adjacent said disc portion and having a coacting serratedclutching surface, means mounting said annular member for rotation intorque-transmitting relation with said other torque-transmitting elementand for axial movement relative to said shaft and said first clutchmember, spring means normally urging said annular member toward saidfirst clutch member to maintain said serrated surfaces in clutchingengagement to transmit torque between said elements, said spring meansbeing yieldable under overload conditions on said serrated faces topermit axial movement of said annular member out of said clutching andtorque-transmitting engagement, said first clutch member having a hubportion secured to said shaft and extending through said annular member,the walls of the opening in said annular member being spaced asubstantial distance from the surrounded hub portion, said spring meanscomprising a coil compression spring surrounding said shaft.

MARTIN A. RICHARDSON.

REFERENCES CITED --The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 954,774 Beard Apr. 12, 19102,333,553 Potgieter et a1 Nov. 2, 1943 2,366,841 Dodge Jan. 9, 19452,375,020 Mitchell May 1, 1945 FOREIGN PATENTS Number Country Date418,543 Great Britain 1934 607,351 Germany i 1934

